Spatiotemporally continuous temperature monitoring using optical fibers (Loop2) in the ground surface and subsurface for the various forest areas, open areas, and the slope in Alaska from 2016 to 2019

A fiber-optic DTS (distributed temperature sensing) system using Raman-scattering optical time domain reflectometry was installed at a research site in interior Alaska (Poker Flat Research Range) to characterize the spatio-temporal temperature characteristics of surface and subsurface variability associated with heterogeneity in a boreal ecosystem includes diverse forest surface and canopy conditions. This is the first part of the Loop2 measurements, initiated in 2016 and continuing with occasional partial or total interruptions due to several factors. In the Loop2 measurements, fiber-optic cable sensors (multimode, GI50/125, dual-core, 4.0 mm) were deployed more widely across the landscape than in Loop1, with different ground surface cover types in the flat areas and the slope area (i.e., relict thermokarst lakes, open moss, shrub, deciduous mixed forest, dense conifer forest and sparse conifer forest) with high spatiotemporal resolution (0.5 m intervals, every 30 minutes) in the horizontal direction. Loop 2 also includes four Quadrat areas (approximately 30 meters per side) with different surface vegetation types, and temperatures were obtained for the four sides and one diagonal along the ground surface as well as subsurface at a depth of 20 cm. The total cable length is 5.4 km, of which approximately 1 km section is located on a slope, of which diffrence of altitude between the slope start and the top is approximately 150 m. Measurements were taken from July 13, 2016 to February 25, 2019 (893 observation days).